What is the energy of an electromagnetic wave that has a wavelength of 9.0 10-6 m? Use the equation , where hc = 1.99 10-25 J•m. A. 4.5 1019 J B. 1.8 10-30 J C. 1.1 10-24 J D. 2.2 10-20 J

The energy of the electromagnetic wave is 2.2 × 10⁻²⁰ J

D. is the correct option

Explanation:

The energy of an electromagnetic wave can be calculated from

Where is Planck's constant, ( 6.626 × 10⁻³⁴ m²kg/s )

is the frequency of radiation

is also given by

where is the velocity of electromagnetic radiation (EMR) / speed of light

( 3.0 × 10⁸ m/s)

and is the wavelength

Hence, we can write

From the question, hc = 1.99 × 10⁻²⁵ J•m

Also, the wavelength, 9.0 × 10⁻⁶ m

Hence,

becomes

∴

Hence, the energy of the electromagnetic wave is 2.2 × 10⁻²⁰ J

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